Android4.3按键消息处理与之前的版本有稍微的区别,基本原理还是一样的,这里主要从两个阶段来分析:
1.前期的准备工作,即开机时启动相应的的线程,静候按键事件的来临
2.当有按键消息时,进行消息的分发等处理
先看一张类图:
从类图中看出,主要涉及到的类有PhoneWindowManager、WindowManagerService、inputManagerService、 InputManager
先看第一个问题,前期的准备工作:
1.开机时先启动inputManagerService,由ServerThread负责启动;
inputManager = new InputManagerService(context, wmHandler); Slog.i(TAG, "Window Manager"); wm = WindowManagerService.main(context, power, display, inputManager, uiHandler, wmHandler, factoryTest != SystemServer.FACTORY_TEST_LOW_LEVEL, !firstBoot, onlyCore); ServiceManager.addService(Context.WINDOW_SERVICE, wm); ServiceManager.addService(Context.INPUT_SERVICE, inputManager); ActivityManagerService.self().setWindowManager(wm); inputManager.setWindowManagerCallbacks(wm.getInputMonitor()); inputManager.start();
看inputManagerService的构造函数:
public InputManagerService(Context context, Handler handler) { this.mContext = context; this.mHandler = new InputManagerHandler(handler.getLooper()); mUseDevInputEventForAudioJack = context.getResources().getBoolean(R.bool.config_useDevInputEventForAudioJack); Slog.i(TAG, "Initializing input manager, mUseDevInputEventForAudioJack=" + mUseDevInputEventForAudioJack); mPtr = nativeInit(this, mContext, mHandler.getLooper().getQueue()); }
先new一个InputManagerHandler,然后调用一个native方法,把service和handler的消息队列作为参数传入,
nativeInit对应是com_android_server_input_InputManagerService.cpp中的nativeInit,,这个通过JNI的机制进行关联。
这里不多说,看nativeInit:
static jint nativeInit(JNIEnv* env, jclass clazz, jobject serviceObj, jobject contextObj, jobject messageQueueObj) { sp<MessageQueue> messageQueue = android_os_MessageQueue_getMessageQueue(env, messageQueueObj); if (messageQueue == NULL) { jniThrowRuntimeException(env, "MessageQueue is not initialized."); return 0; } NativeInputManager* im = new NativeInputManager(contextObj, serviceObj, messageQueue->getLooper()); im->incStrong(0); return reinterpret_cast<jint>(im); }
这里主要是创建一个NativeInputManager对象,看起构造函数:
NativeInputManager::NativeInputManager(jobject contextObj, jobject serviceObj, const sp<Looper>& looper) : mLooper(looper) { JNIEnv* env = jniEnv(); mContextObj = env->NewGlobalRef(contextObj); mServiceObj = env->NewGlobalRef(serviceObj); { AutoMutex _l(mLock); mLocked.systemUiVisibility = ASYSTEM_UI_VISIBILITY_STATUS_BAR_VISIBLE; mLocked.pointerSpeed = 0; mLocked.pointerGesturesEnabled = true; mLocked.showTouches = false; } sp<EventHub> eventHub = new EventHub(); mInputManager = new InputManager(eventHub, this, this); }
这里主要是创建一个InputManager,看起构造函数:
InputManager::InputManager( const sp<EventHubInterface>& eventHub, const sp<InputReaderPolicyInterface>& readerPolicy, const sp<InputDispatcherPolicyInterface>& dispatcherPolicy) { mDispatcher = new InputDispatcher(dispatcherPolicy); mReader = new InputReader(eventHub, readerPolicy, mDispatcher); initialize(); } void InputManager::initialize() { mReaderThread = new InputReaderThread(mReader); mDispatcherThread = new InputDispatcherThread(mDispatcher); }
这里看到了创建对象InputDispatcher 、InputReader以及两个时刻在跑的线程对象:mReaderThread、mDispatcherThread
至此初始化的第一步是完成了,但创建的线程还没start,还开始正真的干活,看开启过程
至此前期的准备工作都做完,两线程开始干活,静候按键事件来临
2.当有按键事件时两个线程处理流程见下图:
两条主线:
a. InputReader从EventHub中获取到按键事件,并通知InputDispatcher;InputDispatcher接到通知后调用
interceptKeyBeforeQueueing方法进行相关的操作,并把按键事件加入到队列中,等待后面处理。
加入队列源码:
bool InputDispatcher::enqueueInboundEventLocked(EventEntry* entry) { bool needWake = mInboundQueue.isEmpty(); mInboundQueue.enqueueAtTail(entry); traceInboundQueueLengthLocked();
b. InputDispatcher从消息队列中获取按键消息,调用interceptKeyBeforeDispatching方法判断是否对此消息进行拦截,
根据其结果进行判断:
nsecs_t delay = mPolicy->interceptKeyBeforeDispatching(commandEntry->inputWindowHandle, &event, entry->policyFlags); mLock.lock(); if (delay < 0) { entry->interceptKeyResult = KeyEntry::INTERCEPT_KEY_RESULT_SKIP; } else if (!delay) { entry->interceptKeyResult = KeyEntry::INTERCEPT_KEY_RESULT_CONTINUE; } else { entry->interceptKeyResult = KeyEntry::INTERCEPT_KEY_RESULT_TRY_AGAIN_LATER; entry->interceptKeyWakeupTime = now() + delay; }
其中在InputDispatcher中调用的interceptKeyBeforeQueueing和interceptKeyBeforeDispatching方法都是对应着
PhoneWindowManager中的同名方法。
android4.3 按键消息处理分析